In view of the unique composition of hair fibers and the numerous changes that occur in styles and fashion, both the waving of hair and the dyeing of hair have long been of particular interest. In particular, hair color alteration by dyeing while permanent waving hair for long-lasting style retention have long been sought by many individuals. However, due to the composition of hair fiber, either the color or curls are not retained as long as desired and the simultaneous permanent waving and dyeing of hair fibers has not yet been achieved by any commercially available product.
In order to best understand the reasons for the inability of the hair fiber to retain curls for substantially long time periods or to be simultaneously permanently waved and colored, it is important to understand that hair is composed of a unique protein material called "keratin" and which is distinguished by the fact that it contains a very significant amount of an amino acid (cystine) which contains the element sulfur in addition to the elements nitrogen, oxygen, carbon and hydrogen. In the natural synthesis of hair, the element sulfur covalently links intra or inter polypeptide chains (K) through two sulfur atoms (S-S) to give keratin protein (K-S-S-K). Only by chemical action can this covalent linkage be broken.
In this regard, many prior art compositions have been developed for the "cold permanent waving" of hair. Typically, these prior art systems treat the hair with a reducing agent which breaks the disulfide (cystine) linkage in the hair. This chemical process typically follows that after the hair is wound around a curling rod.
In general, permanent hair waving is usually carried out by subjecting the hair to reagents containing a free--thiol group e.g., --SH. These materials are also called mercaptans. In this treatment, the hair usually is either wrapped on the rods with water or the lotion containing the thiol, and then saturated with thiol lotion. The thiol waving agent acts to break the disulfide bonds within the hair fiber forming thiol groups in the hair protein and disulfide bonds between two thiol waving agent molecules. The chemistry involved in the reaction of the mercaptan with the cystine disulfide bonds in the hair fiber is illustrated by the following chemical equations: EQU KSSK+2RSH.revreaction.2KSH+RSSR EQU KSSK+RSH.revreaction.KSSR+KSH
When a sufficient number of hair disulfide bonds have been broken, the hair is realigned to pair previously unpaired hair protein thiol groups opposite each other. At this point, the hair is rinsed, removing the unreacted thiol waving agent and any water soluble disulfide reaction products formed from it. Then, the hair is saturated with an oxidizing agent, or neutralizer, such as hydrogen peroxide or bromate salt, to reform disulfide bonds between the newly paired hair protein thiols, thereby giving the hair a new configuration or wave, or adding curl to the hair. By rebonding the sites of the reduced keratin in their new curled configuration, a permanent set which is impervious to water is established.
Much of the rebonding of the reduced sites is accomplished by the action of the chemical oxidizing agent, typically hydrogen peroxide, and can be illustrated by the following chemical reaction: EQU 2 KSH+H.sub.2 O.sub.2 .fwdarw.KSK+2H.sub.2 O
In the art of permanent waving, there is much trial and error, with the hair being over-processed, in some instances. The characteristics of over-processing are raspy feel to the hair or a bleaching of the natural underlying color. Structural evaluation of the hair fiber by physical and chemical analyses usually reveals that the structural integrity of the hair is lessened, which is evidenced by either an increase in the amount of cysteine and cystic acid; a lessening of the cystine content relative to the hair not so processed; or loss of tensile properties.
Some detrimental effect to hair fiber is unavoidable, as the process of permanent waving involves controlled bond scission of the disulfide linkages within the keratin proteins. The recovery of these disulfides is the determining factor for the tightness of the curls and overall tensile strength.
One problem typically encountered with the use of mercaptan reducing agents for the permanent waving of hair is that one lotion strength is needed for virgin hair, while a different lotion strength is needed for damaged or hair that had been previously chemically processed and, hence, difficult to wave. This problem is further compounded when there is a mixture of both damaged as well as normal hair fibers on a head of hair to be permanently waved. In particular, with either oxidatively or deposit colored dyed hair, the subsequent application of mercaptan reducing agents causes a discoloring of the imparted dye in the hair fiber, thereby leaving the hair with an undesired or different shade than had previously existed before the process.
Another problem typically found in the prior art occurs when an individual wishes to dye hair which had been permanently waved. In these circumstances, the dye uptake will usually be uneven from the root to the tip of the hair fibers due to the structural alteration caused to the hair fiber by the permanent wave process.
In practice, this problem is often circumvented by waiting for the hair to "heal", by allowing for a substantial time interval in which aerial oxidation reseals the excessively damaged areas, thereby providing hair fibers which are more amenable to dye uptake in a level manner.
Although the consumer has long sought to have a composition and process which would enable both color and permanent waving to be achieved simultaneously, no prior art system has been able to provide an effective or reliable composition which would enable simultaneous dyeing and permanent waving of hair fibers. In fact, even though this need has existed in the art for decades, no successful commercial product has been attained which satisfies the consumers' need.
One of the difficulties encountered in providing a prior art composition which will achieve this simultaneous dyeing and permanent waving of hair fibers is due to the chemical nature of typical prior art dyestuffs. In general, oxidative dyestuffs are irreversibly altered in their color upon contacting sulfurous materials, such as found in the permanent wave compositions. Consequently, oxidative dyestuffs cannot be successfully employed with permanent waving compositions.
Alternatively, semi-permanent dyestuffs may be employed and have been used to provide a temporary dyeing of the hair. However, such dyestuffs tend to be removed from the hair upon washing and rubbing, or by the increased porosity of hair resulting from chemical processing. Consequently, their incorporation into a permanent waving process does not provide the desired consumer result, since they are incapable of providing the permanent hair coloring effect desired by the consumer.
A further problem found with oxidatives or direct dyes is the fact that these materials are typically irritants or sensitizers of human skin. Consequently, these dyes should be employed either by skilled technicians or home users who are extremely careful to apply the dyes explicitly in accordance with included directions.
Although numerous attempts have been made in the prior art to provide a combined permanent waving and hair dye product, no prior art product has been successful in achieving a universally applicable or a commercially acceptable product.
Representative prior art attempts to meet the commercial demand are found in various prior art patents. Those patent includes U.S. Pat. No. 4,630,621, wherein a common oxidative dyestuff is added to the neutralizing composition for subsequent application to the hair after the hair has been treated with a permanent wave reducing solution. However, as discussed above, such oxidated dyestuffs must be used carefully by skilled technicians or individuals who are extremely cautious and careful with the dyes, due to the irritation that may result on the skin of the user.
In U.S. Pat. No. 4,781,724, a process is disclosed for simultaneously dyeing and permanently waving white and gray hair. Although this patent teaches the incorporation of specific dyestuffs in the permanent wave reducing solution, the dyes taught herein are specifically limited to use on white and gray hair only. In addition, as will be detailed beloW, the operative pH range of the composition incorporating the dyestuffs is substantially greater than the operative pH range of the present invention.
Other prior art patents, such as U.S. Pat. No. 3,299,682, U.K. Patent 1,077,758 and U.S. Pat. No. 4,844,712 teach the use of various dyestuffs. However, these patents do not provide any teaching of combining the dye with a permanent wave composition for achieving simultaneous hair dyeing and permanent waving.
Furthermore, these prior art patents do not, in any way, teach or suggest a permanent waving composition which comprises a pH ranging between 3.0 and 4.5. In fact, any of these prior art references which discuss permanent waving specifically teach away from employing a permanent wave at this particular pH range and, instead, teach compositions wherein the pH is 6.0 or greater.
Therefore, it is a principal object of the present invention to provide a permanent waving composition which is capable of providing substantially tighter curls and longer lasting curls than previously attained in prior art systems.
Another object of the present invention is to provide a permanent waving composition having the characteristic features described above which is also capable of simultaneously dyeing the hair as an integral part of the permanent waving process, when desired by the consumer.
Another object of the present invention is to provide a permanent waving composition and process for application thereof having the characteristic features described above which is capable of providing optimum results at a pH level previously found unsuitable for permanent waving of hair.
Other and more specific objects will in part be obvious and will in part appear hereinafter.